physical properties of matter..introduction (teach)

Introduction to Physical Properties

of Matter

By Moira Whitehouse, PhD

Properties of matter

•are the characteristics of a substance that we can observe such as its color and texture.

Properties of matter

•are characteristics that can be observed using our senses- sight, smell, touch and taste.

•are the characteristics of a substance that you can observe such as its color and texture.

Properties of matter

•are the characteristics of a substance you can observe such as its color and texture.

•are characteristics that can be observed using our senses-sight, smell, touch and taste.

•allow us to distinguish one substance from another.

Let’s look at some of the physical properties of two substances we all know--sugar and sand.

The color of a substance is one of its properties that can be observed using the sense of sight.

Let’s look at some of the physical properties of two substances we all know--sugar and sand.

On the next page you will see photos of sugar and sand. Look at them carefully. What color are they? (be specific)

Let’s look at the physical properties of two common substances we all know-sugar and sand.

The color of a substance is one of its properties that can be observed using the sense of sight.

Color?

If you were specific in your observations, you might have said, “bright snow-white” for sugar and “tan” for sand. Color is one of the properties which allows us to tell which substance is sugar and which is sand.

Another property of a substance is its odor. Anyone who has tried to smell sugar and sand knows that neither one has much of an odor.

What about how it feels—its texture (another property). How does sugar feel when you rub it between your fingers? What about sand?

Most people say that both sugar and sand feel rough and grainy.

Other physical properties of a substance include: •its state of matter at room temperature-- whether it is a solid, liquid or gas•whether or not it is magnetic—attracted to a magnet•whether or not it floats or sinks in water•whether or not it dissolves in water •whether it conducts electricity, heat or sound

Let’s take a look at some of these physical properties of sugar and sand:

•What state of matter is each substance at room temperature?

•Does either sugar or sand dissolve in water?

•Is either sugar or sand attracted to a magnet?

•We will discuss what substances are conductors of electricity and heat in another presentation.

State of matter:

What state of matter is sugar at room temperature? a. solid b. liquid c. gas

What state of matter is sand at room temperature? a. solid b. liquid c. gas

Both sugar and sand are solids at room temperature.

Another physical property of a substance is whether or not it is magnetic.

Ground up pieces of iron are magnetic—attracted to a magnet.

What about sugar and sand. Is either attracted to a magnet? What do you predict? Let’s try it.

What about sugar and sand. Is either sugar or sand attracted to a magnet? What do you predict? Let’s try it.

Sand

Neither sugar nor sand is magnetic. The magnet does not pick up the tiny grains of sugar or sand.

Sand

Solubility--whether or not a substance dissolves in water is another physical property.

Dissolve means to mix evenly. When a solid dissolves in water, the molecules mix evenly and the solid seems to disappear. The resulting liquid is called a solution. When a substance dissolves, it may lose some of its physical properties such as color and feel.

Solubility--whether or not a substance dissolves in water is another physical property of substances.

•If we mix sugar and water and stir, what do you predict?a. The sugar will dissolve in waterb. The sugar will not dissolve in water

•What about if we mix sand and water and stir?

•What do you predict?

a. Sand will dissolve in the waterb. Sand will not dissolve in the water

•Below are the photos of two containers, one with a mixture of sugar and water and the other with a mixture of sand and water. •Circle the photo of sugar and water, and check the one with sand and water. •Write “dissolved” under the correct photo.•Write “solution” under the correct photo.

Sugar mixes evenly with water and dissolves. Sugar and water mixed together form a solution.

As long as we are shaking the sand and water, the two substances mix evenly. But as soon as we stop shaking the container, the sand settles to the bottom of the flask. Sand does not dissolve in water.

Imagine that the molecules of water, sugar and sand have been magnified so we can see them. Circle the diagram that shows molecules of sugar and water? Check the one that shows a mixture of molecules of sand and water? Explain your choices.

When sugar is dissolved in water you can tell the sugar is still there, even though it becomes invisible. How can you tell that sugar is still there?

Aha, yes, you can use your sense of taste or touch. When you take a solution of sugar and water, it tastes sweet. Also, sugar water feels sticky. The sugar is still there. You just cannot see it. When you mix sugar with water the sugar loses its white color and its grainy, rough texture.

Yes, sugar dissolves in water along with other flavors and colors and produces a solution that tastes sweet.

Sugar dissolved in water makes the sweet flavor found in all kinds of soda pop.

candies

or

cookies

tastes SWEET

Sugar mixed with many substances like

Sand and sugar are easy to tell apart. When you look at them you can immediately tell one from the other just by their most obvious physical property—color. But what about two substances that look alike, such as sugar and salt. They have many physical properties in common.

Both:•are snow white, have little or no smell, are solids at room temperature and feel rough and grainy.

•are nonmagnetic—not attracted to a magnet

• dissolve in water.

What physical property allows us to tell the apart?

I’m sure most of you are saying, “And on what planet do you live?” Sugar taste sweet and salt tastes, well, salty.

SWEET SALTY

In summary:

Physical properties of substances

•are observable characteristics of the substances

•allow us to distinguish one substance from another